1. Field of the Invention
The invention relates to a method and compositions for controlling flies and ticks.
2. Description of the Prior Art
Ticks and flies pose a significant risk to the health and welfare of warm-blooded animals, and their resistance to approved acaracides and insecticides threatens efforts to control these pests in the U.S. and elsewhere.
For instance, cattle fever ticks (Boophilus microplus and B. annulatus) are vectors of protozoan parasites of the genus Babesia which are the causative agents of babesiosis and which infect a wide range of vertebrate hosts, including bovine and man. Bovine babesiosis or cattle fever is a particularly serious disease of livestock and domestic animals which historically caused major losses to the cattle industry in the United States. Those losses prompted the U.S. Congress to initiate the Cattle Fever Tick Eradication Program in 1906, which eventually led to the elimination of the cattle fever ticks from the U.S. Unfortunately, tick control efforts in Mexico have not been successful and these ticks remain well established in that country. The reservoir of ticks in Mexico serves as a continuing source of infestation for areas of the U.S. due to the movement of feral, stray, and smuggled animals.
Presently, the cattle tick eradication program relies exclusively on a single organophosphate pesticide, coumaphos, for the treatment of all cattle to prevent the ingress of these ticks into the U.S. However, resistance to coumaphos in Mexican strains of the cattle fever tick B. microplus is threatening the continued success of the eradication program.
The horn fly, Haematobia irritans irritans, is another blood-feeding pest which poses an increasingly serious threat as the result of the development of insecticide resistant strains. The horn fly is currently one of the most serious pests of cattle in the U.S. When large numbers of these flies are on cattle, the animals will bunch and expend considerable effort fighting the flies, thereby preventing the animals from feeding normally. Studies in the U.S. and Canada have shown that horn fly infested cattle exhibit significantly lower weight gain and reduced milk production than non-infested animals. Traditional methods for control of horn flies have included insecticide-impregnated ear tags, dusting, oiling and spraying animals with various insecticides. At one time, pyrethroids were highly effective, although resistant populations spread rapidly, supplanting the pyrethroid-sensitive populations throughout the U.S. within three years. As a result, more organophosphate pesticides have been used to control horn flies. However, diazinon resistant horn flies have now been found in the U.S., and the failure of horn fly control with diazinon tags has been reported after just three years of use.
As a result of the spread of pesticide-resistant strains of these and other ticks and flies, there is a growing need to develop improved tools for their control.